function setScrollBars(contentID, scrollID)
{
    var cobj = document.getElementById(contentID);
    var sobj = document.getElementById(scrollID);

    if ( cobj.scrollHeight > cobj.offsetHeight )
	sobj.style.display = "block";
    else
	sobj.style.display = "none";
}

var scrollId;
var scrollAmt;

function start_scroll (contentID, amt)
{
    var cobj = document.getElementById(contentID);
    stop_scroll();

    if ( ! cobj || cobj.style.display == "none" )
	return;

    scrollAmt = amt;
    scrollId = setInterval ("scroll('" + contentID + "')", 50);
}

function stop_scroll ()
{
    if ( scrollId )
    {
	clearInterval (scrollId);
	scrollId = undefined;
    }
}

function scroll_amt (amt)
{
    scrollAmt = amt;
}

function scroll (contentID)
{
    var cobj = document.getElementById(contentID);

    cobj.scrollTop += scrollAmt;

    if ( scrollAmt < 0 )
    {
	if ( cobj.scrollTop == 0 )
	    stop_scroll();
    }
    else 
    {
	if ( cobj.scrollTop == cobj.scrollHeight )
	    stop_scroll();
    }
}